1. Field of the Invention
The present invention relates to a signal conversion device applicable to the Subscriber Identify Module (SIM), and more particularly, to the technical field regarding the integration of dual cards.
2. Description of the Prior Art
With the internationalization of corporations, efficiency is the key to competing successfully in the global market, thus the mobile phone has become the most important gadget for businessmen/women. For one who is about to embark on a short-term business trip, s/he needs to get a phone number from a local telecommunication service provider so as to save international roaming fees. In the past, a businessman/woman either carried two mobile phones or swapped SIM cards repetitively while on a business trip abroad, and that was not only inconvenient but also inefficient. Today, both mobile network operators and telecommunication service providers provide services regarding dual SIM mobile phones so as to facilitate reducing international mobile phone fees. Currently, a SIM card is used in a mobile phone to store the user's phone number, phone book and system information, such as the Personal Identification Number (PIN) code and user ID, and to perform antitheft function, access control function, etc. However, people's heavy reliance on mobile phones gives rise to the needs to integrate the near field communication (NFC) functions, such as the functions of EasyCard, credit card and entrance card, into a SIM card, and this means the SIM card requires a greater capacity. The SIM Application Toolkit (STK) is a standard of the Global System for Mobile Communications (GSM), which defines the interface between a SIM card and a mobile phone as well as the operating procedure. Specifically, the STK is a standard interface tool for developing application service on a SIM card that enables applications in the SIM card to be operated by any mobile phone.
Among the developed technologies is a technology that employs the flexible printed circuit (FPC) technology to fabricate a smart card. Accordingly, the smart card can be seamlessly attached to the SIM card provided by another telecommunication service provider and then be inserted into the mobile phone along with the SIM card. The smart card comprises an IC chip loaded with software that enhances a SIM card's functionality, facilitates the integration of relevant value-added services and enables the user to shift between different phone numbers by means of the STK. According to the prior technologies, the IC chip of the smart card is attached to the flexible printed circuit board by means of the flip-chip technology. However, the prior art technologies involve processing the SIM card from the telecommunication service provider due to the thinness of the IC chip. In other words, forming an opening on the SIM card to which the smart card is to be attached is required, and the opening should conform to the size of the IC chip so that the IC chip can be snapped therein seamlessly. The requirement of an opening means the SIM card to which the smart card is to be attached must undergo a destructive procedure, and this may provoke disputes between the user and the telecommunication service provider later on, causing much inconvenience to the user.